Equalizing loads on motor-generator sets.



PATENTED MAY 28, 1907.

. ,w. m r m 1W MI HUN. .0 b H I T v. i E k N a m r m A c .L E T A Twill W A fi h k 1 r L i m mw a W y AN 5 \Q B APPLICATION FILED OUT. 11. 1904.

NWE

JO N B. TAYLOR, or ISOHENECTADY,

NEW

ELECTRIC COMPANY, -A CORPORATION OF NEW YORK.

IEQUALIZING LOADS ON Moron-GENERATOR SETS.

Nest-sews.

Specification of Letters Patent.

Patented. May as, 1907.

Application filed October 11,1904. Serial No. 228,067.

To all whom it may concern:

Be it known that I, JOHN B. TAYLOR, a citizen of the United States, residing at Schenec- Generator Sets,

tad'y, county of Schenectady, State of New York, have invented certain new and useful Improvements in Equalizing Loads on Motorof which the following is a specification.

en a motor generator set consisting of arr-alternating current generator and a synchronous motor is run in multiple on both sides with another set of the same construction, considerable difficulty is frequently ex perienced in equalizing or adjusting the portion of the load carried by one set with that carried by the other: I This is due to diferent characteristics of machines of different sizes, also to mechanical difiiculties in constructing the machine so as to obtain the same relative positions between the stationary and moving parts of the erators of the two sets.

motor gen- For instance, when the motors of the twosets are running from the same mains, the generators being separated, the electromotive force wave of one generator. may be slightly in advance of the other, so that when connected in multiple one machine will tend'to carry-more load than the other. Under these conditionschanging the field excitation has little'or no effect on the division of the load between the two machines and tends merely to cause leading and lagging'currents.

In order to overcome the difliculties above set forth I provide means whereby the phases of the currents supplied to the motors of the motor generator sets may be shifted. By utilizing this means to shift the hases of the 'electrornotive forces" impresse upon the motor of. one of the motor generator sets, the load of this set may be adjusted so as to form a proper proportion of the total load carried by-the two or. more sets.

' The novel features of the invention I have pointed out with particularity in the appended claims.

The-invention itself, however, both as to its embodiment and-mode of operation, will be better understood by reference to-the following descriptiontaken in connection with the accompanying drawings, in which.

Figure 1 representsasystem embodying my invention, and Fig, 2 a modification.

. In Fig. 1 the alternating current supply YORK, ASSIGNOR TO GENERAL usual three-phase high potential alternating current. The motor-generator sets which receive current from these transmission lines and which are to be run in multiple with each other are indicated at 4 and 5. The motor of set 4 is indicated at 6 and the generator at 7, while in the case of set 5 the motor is'indicated at 8 and the generator at 9.

The conditions which require the use of such motor'generator sets are generally such as/involve the transformation of alternating current of one frequency into current of another frequency, as for example, the transformation of current of 25 cycles, suitable for power purposes, into cycle current, suitable for lighting. 'VVhere the motor generator sets are direct connectedthe number of poles ofthe respective machines are in the ratio of 25 to 60. It will therefore be evident that a phase displacement of the 25 cycle machine, even if of only a few degrees, will correspond approximately to a two and one-half times greater phase displacement on the 60 cycle generator.

In order to divide the load properly between the generators of the motorgenerator' sets, it is therefore evident that only a small phase displacement is necessary on the motor sides of the sets. I provide means, however, for

hase on the motor sides of the sets, either arge or small, in order to secure the desired results. This means, as shown,- consists of taps on the transformers which sup ly the motor generator sets, which ta s, as t nections thereto are shifte enable the phases of the currents likewise to be shifted. 5

In Fig. 1 the rimary windings of a threehase connected set ofsingle phase transormers or of a single three-phase transformer, are indicated at 10,11 and;12,.and the corresponding secondaries at 113, 14- and 15. The sets of windings are shownas connected in delta relation'to each other.' The secondary windings are provided, near their,

7 unction points, with a series of taps to which be made to the supply connections may leads 16, 17 and 18 of the motors by means ofcorresponding switch arms, or other suitable devices 19, 20 and 21. motor generator set 4', these switches are ar ranged so as to connect the leads 16, 17 and In the case of theproducing any desired shifting in e conmade to points in the main 'windings.

connection farther of the coils;

18 to the junction between the respective coils 13, 14 and 15. a

The motor generator set 5 is supplied with current from the three-phase transformer windings-22, 23 and 24. These windings are the same as-the windings 13, 14 and 15 already deseribed,-and the tap. connections are likewise the same. The leads 25, 26 and 27, however, are shown as connected. by switches, not tothe junction between the windings, but to taps displaced from the terminals of the winding. This has the effect of impressing 11 on themotor generator set voltages, the pfiases and magnitudes of which are indicated bythe dotted triangle 28. The phase of these voltages, it will be seen, are shifted slightly from the corresponding phases'of the windings themselves, and if desired may be shifted still 'more by shiftingthe points of away from the terminals .By' this shifting the connections of the leads 25, 26 and 27 to one side or the other of the respective junction points, the electromotive forces impressed upon the motor 8 may be advanced or retarded in phase, as the case may be, until the load taken by the motor-generator set bears a proper proportion of the total load carried all of the' sets. It will be noted that in the case just described thevoltages, as. their phases are shifted from the normal voltage of the transformer secondaries, decrease in value. I

may, however, if desired, arrange the con' nections so as to produce an increase in value as well as a decrease. Thus in Fig. 2, which in all other respects isintended, as far as it goes, to be the same as Fig. 1, the transformer secondaries 29, 30 and 31 are provided respectively with-extensions of the main windings indicated at 32, 33 and 34.

These extensions, as well as adjacent points of the corresponding main windings, are provided with taps, so that the leads conveying current from the windings may be connected either to the extensions or to portions of the main windings nearv with each other. When the leads are con nected to the extensions the voltages, in magnitude and phase, are represented, in the case of connection to one set of taps, bythe dotted triangle 35, while by wayof contrast the voltages corresponding to connections to points in the mam windlngs'are represented by the dotted triangle 36. The voltages, when connection is made to the-extensions are greater inmagnitude' than the voltages y choosing connections their points of junction between one extreme and the other a considerable variation in secured, and thereby provide adjusting means for any probable requirements in connection with load equalization.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The combination of an alternating cur rent supply system, a plurality of sets of motor-generators, transformers between said sets and said supply S VS1101T1, and means for I shifting the connections of at least one of said motor generators with the transformer from which it receives current.

2. The combination of a transformer, a motor generator set consisting of a synchronous motor coupled to an alternating current chronous motor and said transformer, and means for shifting the phase of the voltage supplied from said transformer to said synchronous motor.

synchronous motor, an alternating current generator driven thereby, and phase shifting connections between said motor and said transformer.

4. The combination of transformer windings, a plurality of taps extending from each winding, a plurality of related dynamo electric machines, and leads extending from one of said machines and adapted to be conphase differing relations.

5. The combination of an alternating current supply system, a plurality of synchronous motor generators, and means for adjusting the phase of at least one of said motor generators with respect to another of said motor generators. v

6. The combination of an alternating current supply system, dynamo electric machines driven therefrom in synchronism, and means for adjusting the phase of one machine with respect to another.

rent supply system, a plurality of dynamo machines for transforming current from said system, said dynamo machines operating to feed the transformed current to a common receivingcirc'uit, and means foriadjusting the ratio between the loads taken by-said machines In witness whereof I have hereunto hand this tenth day of October, 1904.

JOHN B; TAYLOR. f .Witnesses:

EDWARD WILLIAMs, J12, HELEN ORFORD.

phase and magnitude of the voltages may be generator, connections between said syn- 7. The combination of an alternating-cur 3. The combination of a transformer, a i

nected to said windings in aplurality of setmy 

